(1) Field of the Invention
The present invention relates to a reel spring of a video tape cassette. In particular, the present invention relates to a reel spring having embossed guide grooves for supporting pivots of a tape reel, the guide grooves being formed formed on end portions of the reel spring without the increase in materials or decrease in tension whereby the pivots are not alienated from the end portion even though the width of a reel spring is narrow.
(2) Description of the Prior Art
A reel spring which is installed in an upper housing is a part for smoothing the drive of a reel by pressing the reel with a given resilience.
The technique relating to such a reel spring has been disclosed in U.S. Pat. No. 4,770,367 to William M. Carroll. This Patent is for a reel spring which has a substantially diamond-like configuration and provides a structure suitable for mass-producing and minimizing material loss.
In order to obtain the above object, the structure of this patent has the function of reel springs comprising an elongated strip of resilient material formed in a generally rectangular configuration. More particularly, this structure is achieved by a base portion having apertures for mounting the reel spring on an upper cassette housing; transition sections extending at a first angle to the plane of the base portion; and end portions extending at a second angle to the plane of the transition sections.
In such conventional spring, the end portions contacting protruding pivots of the reel are formed flatly, and the width of the end portions of the reel spring must be broad in order not to be alienated from the end portions when the pivots run. Otherwise at the time of the drive of the tape the pivots run and may be alienated from the end portions. Making the width of the end portions broadly enough to prevent the above problem causes a greater amount of material waste compared to a reel spring of an elongated strip having the same width, and therefore it is hard to reduce the manufacturing cost.
Another prior art technology for solving these problems is disclosed in Korean Publication No. 89-7595. The structure relating to end portions of the above conventional reel spring is shown in FIG. 6. A reel spring 4 shown in FIG. 6 has embossed guide grooves 6 on its end portions 5. The size of these embossed guide grooves 6 is formed to be substantially the same as that of the circumference of protruding pivots 3.
In consequence there is no space where the pivots 3 can run in the guide grooves 6, and when the reel 2 is driven, the pivots come to run into the inside wall of the guide grooves 6.
Accordingly an excessive force presses upon the drive of the tape and when high speed driving the pivots come into contact with one side of the guide grooves thereby causes a disadvantage that the pivots of plastics are deformed by friction.